1. Technical Field
The present invention provides a method and structure for changing the electrical resistance of a resistor.
2. Related Art
A resistor on a wafer may have its electrical resistance trimmed by using laser ablation to remove a portion of the resistor. For example, the laser ablation may cut slots in the resistor. With existing technology, however, trimming a resistor by using laser ablation requires the resistor to have dimensions on the order of tens of microns, which is large enough to be compatible with the laser spot dimension and laser alignment. A method is needed to trim a resistor having dimensions at a micron or sub-micron level.
The present invention provides a method for changing an electrical resistance of a resistor, comprising:
providing a resistor having a length L and a first electrical resistance R1; and
exposing a portion of the resistor to a laser radiation for a time of exposure, wherein the portion of the resistor includes a fraction F of the length L, wherein at an end of the time of exposure the resistor has a second electrical resistance R2, and wherein R2 is unequal to R1.
The present invention provides an electrical structure, comprising:
a resistor having a length L and an electrical resistance R(t) at a time t; and
a laser radiation directed onto a portion of the resistor, wherein the portion of the resistor includes a fraction F of the length L, and wherein the laser radiation heats the portion of the resistor such that the electrical resistance R(t) instantaneously changes at a rate dR/dt.
The present invention provides an electrical resistor of length L, comprising N layers denoted as layers 1, 2, . . . , N:
wherein a portion of the resistor includes a fraction F of the length L;
wherein N is at least 2;
wherein layer I includes an electrically conductive material MI for I=1, 2, . . . , N;
wherein layer J is in electrically conductive contact with layer J+1 for J=1, 2, . . . , Nxe2x88x921; and
wherein a cell CK,K+1 couples a cell CKxe2x80x2 of the layer K to a cell CK+1xe2x80x2 of the layer K+1, wherein the cell CKxe2x80x2 is within the portion of the resistor and includes the material MK, wherein the cell CK+1xe2x80x2 is within the portion of the resistor and includes the material M+1, wherein the cell CK,K+1 is within the portion of the resistor and includes an electrically conductive material MK,K+1 that comprises a chemical combination of the material MK from the layer K and the material MK+1 from the layer K+1, and wherein K is selected from the group consisting of 1, 2, . . . , Nxe2x88x921, and combinations thereof.
The present invention provides an electrical resistor of length L, comprising:
a first portion having a length L1, wherein the first portion includes at least one cell having an electrically conductive material with a first structure; and
a second portion of length L2 such that L2=Lxe2x88x92L1, wherein the second portion includes a fraction F of the length L such that F=L2/L, wherein the second portion includes a structured cell having the electrically conductive material with a second structure, and wherein the electrically conductive material with the second structure has resulted from a laser heating of the electrically conductive material with the first structure.
The present invention provides a method for changing an electrical resistance of a resistor having dimensions at a micron or sub-micron level.